CLACE - CLoud and Aerosol Characterization Experiment

View from Jungfraujoch over the Aletsch glacier. Picture: J. Schneider, MPIC.

CLACE-3 (2004), CLACE-4 (2005), CLACE-5 (2006), CLACE-6 (2007)

CLACE-3 and CLACE-4 were the third and forth in a series of experiments held at the high alpine research station Jungfraujoch (JFJ, 3580 m asl; 46.55oN, 7.98oE), Switzerland. The experiments were designed to investigate the chemical composition of aerosol particles, their hygroscopic properties, their light scattering properties, and their interaction with both liquid and ice phase clouds. These measurements thus contribute to a greater understanding of both the direct and indirect effect of aerosols on climate.
During CLACE-3 in February/March 2004, our group performed mass spectrometric measurements of residuals of supercooled cloud droplets and ice nuclei, using the Aerodyne Quadrupole Aerosol Mass Spectrometer (Q-AMS). A novel sampling system for freshly formed ice particles (Ice-CVI, S. Mertes, TROPOS) was coupled to the Q-AMS. By presegregation of other mixed-phase cloud constituents and evaporation of the ice fraction, the residual particles, which are expected to be the original ice nuclei, were made available for analysis with the Q-AMS. Depending on cloud type and Ice-CVI operation mode, the combination of Q-AMS and Ice-CVI allowed to analyze the residuals of ice particles as well as of supercooled cloud droplets. Alternatively, the interstitial aerosol was sampled and compared to the residual particles.
These measurements were repeated with a similar setup in CLACE-4 in February/March 2005.
In the following year (Feb-Mar 2006), we conducted CLACE-5, which was a project coordinated by the Particle Chemistry Department as part of the "Sonderforschungsbereich (SFB) 641 TROPEIS". In CLACE-5, the instrumentation included (amongst others) an Aerodyne W-ToF-AMS, a TSI ATOFMS (operated by ETH Zürich) and the SPLAT (Single Particle Laser Ablation Time-of-Flight Mass Spectrometer) which has been developed in our department.
CLACE-6 was conducted in Feb-Mar 2007, again as part of the "Sonderforschungsbereich (SFB) 641 TROPEIS", coordinated by Prof. Joachim Curtius from Goethe University Frankfurt.

In 2013 and 2017, we returned to the Jungfraujoch for the INUIT project.

Instrumentation
CLACE-3/4: Aerodyne Q-AMS, PALAS OPC 2010, Grimm OPC 1.108, TSI CPC 3010, 3025
CLACE-5: Aerodyne ToF-AMS, SPLAT, Grimm OPCs 1.108 and 1.109, MAAP, TSI CPC 3025
CLACE-6: Aerodyne ToF-AMS, SPLAT, Grimm OPC 1.108, MAAP, TSI CPCs 3025 & 3010

People involved:
CLACE-3: J. Schneider, T. Böttger, S. Walter, N. Hock, J. Curtius
CLACE-4: J. Schneider, S. Walter
CLACE-5: J. Curtius, J. Schneider, F. Drewnick, H.-J. Vössing, M. Kamphus, M. Ettner-Mahl, S. Walter, S. Raupach, T. Böttger, W. Schneider
CLACE-6: J. Curtius, J. Schneider, M. Kamphus, M. Ettner-Mahl, S. Walter, T. Böttger, Chr. von Glahn

Results:

Mertes, S., B. Verheggen, S. Walter, P. Connolly, M. Ebert, J. Schneider, K.N. Bower, M. Inerle-Hof, J. Cozic, U. Baltensperger and E. Weingartner, Counterflow virtual impactor based collection of small ice particles in mixed-phase clouds for the physico-chemical characterization of tropospheric ice nuclei: sampler description and first case study, Aerosol Sci. Technol., 41, 848-864, doi: 10.1080/02786820701501881, 2007.

Cozic, J., S. Mertes, B. Verheggen, D. J. Cziczo, S. J. Gallavardin, S. Walter, U. Baltensperger, and E. Weingartner, Field observations of black carbon enrichment in atmospheric ice particle residuals suggesting a potential ice nucleating capability,  J. Geophys. Res., 113, D15209, doi:10.1029/2007JD009266, 2008.

Cziczo, D. J., Stetzer, O., Worringen, A., Ebert, M., Weinbruch, S., Kamphus, M., Gallavardin, S. J., Curtius, J., Borrmann, S., Froyd, K. D., Mertes, S., Mohler, O., and Lohmann, U.: Inadvertent climate modification due to anthropogenic lead, Nature Geoscience, 2, 333-336, https://doi.org/10.1038/ngeo499, 2009.

Kamphus, M., Ettner-Mahl, M., Klimach, T., Drewnick, F., Keller, L., Cziczo, D. J., Mertes, S., Borrmann, S., and Curtius, J.: Chemical composition of ambient aerosol, ice residues and cloud droplet residues in mixed-phase clouds: single particle analysis during the Cloud and Aerosol Characterization Experiment (CLACE 6), Atmos. Chem. Phys., 10, 8077–8095, https://doi.org/10.5194/acp-10-8077-2010, 2010.

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